Automotive engineers have increasingly utilized plastic materials in developing various engine components, including the intake manifold. Unlike prior aluminum manifolds, which have a high vibration dampening effect, plastic manifolds tend to vibrate more readily as high velocity air flows therethrough resulting in excessive noise.
To reduce such noise, prior art intake systems require elaborate silencing methods which, if incorporated into a modern internal combustion engine, require substantial packaging and/or redesign of the engine. The inventors of the present invention have found that a silencer connected between the outlet of the idle air bypass valve and the intake manifold is sufficient to reduce noise generation in the intake manifold. In addition, the apparatus may be incorporated onto existing engines, thereby allowing for field serviceability.
Copending U.S. patent application, Ser. No. 964,793, assigned to the assignee of the present invention, which is incorporated herein by reference, introduces a housing with a number of perforations to control this noise. Although effective, the plate may increase package space and cost in some applications.